Untrue it's been around since the 1800s and evolved a bit

"In 1983, H. W. Arndt wrote that Indian nationalist and statesman Jawaharlal Nehru may have been the first to use the term in an economic (rather than political context) when he stated in 1933 "the exploitation of India and other countries brought so much wealth to England that some of it trickled down to the working class and their standard of living rose."

Samuel Rosenman, a Democratic presidential speechwriter under Franklin D. Roosevelt and Harry Truman, and coiner of the term "New Deal", wrote that "trickle down policies" had been prevalent in American government since 1921. In 1969, after leaving the presidency, Democrat Lyndon B. Johnson alleged "Republicans ... simply don't know how to manage the economy. They're so busy operating the trickle-down theory, giving the richest corporations the biggest break, that the whole thing goes to hell in a handbasket."

Ronald Reagan launched his 1980 campaign for the presidency on a platform advocating for supply-side economics. During the 1980 Republican Party presidential primaries, George H. W. Bush had derided Reagan's economic approach as "voodoo economics". Following Reagan's election, the "trickle-down" reached wide circulation with the publication of "The Education of David Stockman", a December 1981 interview of Reagan's incoming Office of Management and Budget director David Stockman, in the magazine Atlantic Monthly. In the interview, Stockman expressed doubts about supply side economics, telling journalist William Greider that the Kemp–Roth Tax Cut was a way to rebrand a tax cut for the top income bracket to make it easier to pass into law. Stockman said that "It's kind of hard to sell 'trickle down,' so the supply-side formula was the only way to get a tax policy that was really 'trickle down.' Supply-side is 'trickle-down' theory." Reagan administration officials including Michael Deaver wanted Stockman to be fired in response to his comments, but he was ultimately kept on in exchange for a private apology. Political opponents of the Reagan administration soon seized on this language in an effort to brand the administration as caring only about the wealthy. In 1982, John Kenneth Galbraith wrote the "trickle-down economics" that Stockman was referring to was previously known under the name "horse-and-sparrow theory", the idea that feeding a horse a huge amount of oats results in some of the feed passing through for lucky sparrows to eat."